The state has begun a pilot project to test a new process of rebuilding saltwater marshes known as thin layer placement where sediments removed from waterways are sprayed back onto marshes in an effort to raise their elevation and make them more resilient to erosion and rising sea levels.
(Staff Photo by Phillip Tomlinson | South Jersey Times)

DOWNE TWP. - The New Jersey Department of Environmental Protection announced this week that the state, along with the Army Corps of Engineers and other partners has begun a pilot project to test a new method of saltwater marsh replenishment.

Funding for the multi-phase project comes from the U.S. Department of Interior, as well as the Army Corps of Engineers, the NJ Department of Transportation, the Nature Conservancy and the Green Trust Alliance. Monitoring and analysis of the project's economic and ecological benefits will be provided by Rutgers University.

The first phase of the project began last week on a small patch of meadow in Cape May County and will expand to encompass areas of Avalon and Fortescue in Downe Township.

Known as thin layer placement, the new process involves spraying clean dredge spoils onto a wetland in thin layers, building up the elevation of marshes without damaging or destroying the vegetative growth that knits them together.

Marshes naturally replenish themselves over time, but many marshlands have lost significant elevation in recent decades due to a number of factors including sea-level rise and a geological process known as isostatic subsidence.

"We are losing marshes to a lot of factors," said NJDEP spokesman Larry Hajna. "Areas that were elevated are now becoming open water."

The thin layer placement process builds up the marshes gradually with a layered application of materials that were washed off of them by rains and tides.

Replenishing the marshes will help to protect vital habitat that is home to a wide variety of species, including various types of shore birds that nest in the spartina grasses that make up healthy marshes.

Marshes also help keep water supplies clean and provide a protective barrier for inland areas, absorbing large amounts of water and lessening the impact of storm surges.

Dredge spoils are the alluvial sediments that are pumped out of tidal waterways. For years the state removed them from the ecosystem entirely, confining them in disposal pits. The process of transporting the removed sand and silt to the storage sites is costly, and the unsightly facilities take up large amounts of space.

The state's hesitance to use dredge spoils came from concerns about contaminants that may have settled into the bottoms of rivers and creek beds.

For this project, and subsequent efforts, the state will take pains to assure that all dredged materials returned to the marshes will be thoroughly tested and free of contaminants, according to a statement released by the NJDEP.

"The process will use clean materials that are being washed off of these elevated marshes," said Hajna. "The idea is to keep them in the ecosystem."

The process also has an ancillary benefit of keeping waterways navigable.

"We are very excited about this project and believe it has the potential to provide many benefits in a cost-effective and environmentally responsible manner," NJDEP Commissioner Bob Martin said in a release."It has the potential to make coastal communities more storm resilient while helping to solve the problem of where to dispose of sediment that builds up and impedes navigation in our waterways.

"As an added benefit, this will create places for birds to nest, including the state-endangered black skimmer."

According the NJDEP, the spoils used in the Fortescue phase of the project will come from Fortescue Creek, which is vital to the community's recreational fishing businesses.

The creek has been severely impacted by shoaling in recent years, and the charter boats that operate out of the marina there have had difficulty getting in and out on lower tides.

"Even a small boat has trouble getting in and out on low tide now," said Downe Township mayor Bob Campbell.

"We're trying to get Fortescue Creek dredged right now."

Should the pilot project prove successful, it may be a solution to two distinct problems that threaten Fortescue and other coastal communities throughout the state.

The restoration effort also compliment beach replenishment and shoreline protection efforts that are being undertaken in the coming year by Downe Township in conjunction with FEMA, as well as various local and regional environmental commissions and non-profit organizations.